Overflow pans for water heaters have been conventionally made of galvanized steel with bottom and side walls interconnected by a suitable interlocking seam. A nipple of coupling is normally provided through the side wall for connection with a drain to remove water leaking from the heater into the pan. Not only are units of this type unsightly but they are extremely difficult to clean and the seam normally collects dirt which is very difficult to remove. Additionally, the outside of the seam, where the pan rests on the supporting surface, is often uneven and dirt is difficult to remove from this area so that the installation becomes more and more unsightly as time goes on. Additionally, galvanized pans of this type are likely to rust through at concealed areas under the heater, and such rusting is normally not detected until the heater leaks, whereupon water flows from the pan onto the supporting surface rather than through the nipple and drain. Pans of this type are rather expensive to purchase, primarily because of the labor costs involved in their manufacture, and all too often have an unfortunately short life because of rusting.